Television – Bandwidth reduction system
Reexamination Certificate
1998-02-20
2002-07-09
Harvey, David E. (Department: 2614)
Television
Bandwidth reduction system
C348S014120, C348S723000, C348S565000
Reexamination Certificate
active
06417886
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image transmission apparatus and method and an image transmission system, more particularly to techniques of displaying image signals transmitted from a plurality of apparatuses on the same screen of a remotely located apparatus.
2. Related Background Art
A system is being developed in which images taken with a plurality of cameras are displayed at the same time on the screen of a single monitor located remotely from the cameras, by using a picture-in-picture method or the like. Such a system is widely used for monitoring or other applications, and all image signals picked up by cameras are transmitted via wired or wireless transmission paths to the monitor. Such an image transmission system will be described with reference to
FIGS. 1 and 2
.
FIGS. 1 and 2
are schematic diagrams showing conventional image transmission systems.
FIG. 1
shows a system using wired transmission paths, whereas
FIG. 2
shows a system using wireless transmission paths.
In
FIG. 1
, a first camera unit
102
and a second camera unit
103
are connected via wired transmission paths
106
to a monitor unit
101
.
The monitor unit
101
receives an image signal generated by the first camera unit
102
which picked up an image of an object
104
, and an image signal generated by the second camera unit
103
which picked up an image of an object
105
. These image signals are synthesized to display it on the same screen. In the example shown in
FIG. 1
, the image of the object
104
picked up with the first camera unit
102
is displayed in a main screen area of the monitor unit
101
, whereas the image of the object
105
picked up with the second camera unit
103
is displayed in a partial screen area of the monitor unit
101
, being superposed upon the image of the object
104
. In the following, a screen area occupying 50% or more of the effective display area of the screen of the monitor unit
101
is called a main image plane, whereas the screen area not occupied by the main image plane is called a sub image plane.
In
FIG. 2
, a monitor unit
101
, a first camera unit
102
, and a second camera unit
103
each equipped with a wireless communication unit
206
. The first and second camera units
102
and
103
transmit image signals from the communication units
206
to the monitor unit
101
. The monitor unit
101
receives an image signal generated by the first camera unit
102
which picked up an image of an object
104
, and an image signal generated by the second camera unit
103
which picked up an image of an object
105
. These image signals are synthesized to display it on the same screen. In the example shown in
FIG. 2
, the monitor unit
101
displays the image of the subject
104
picked up with the first camera unit
102
, in the main image plane, and displays the image of the subject
105
picked up with the second camera unit
103
, in the sub image plane being superposed on the main image plane.
Next, the structures of the monitor unit
101
, first camera unit
102
and second camera unit
103
will be described with reference to FIG.
3
.
In the first camera unit
102
shown in
FIG. 3
, a camera unit A
103
picks up an optical image of the subject
104
to generate an electrical signal of a predetermined type. A signal processing unit A
302
digitizes the electrical signal supplied from the camera unit A
301
to convert it into an image signal of a predetermined format. The image signal converted by the signal processing unit A
302
is an image signal matching a size of an effective display area of the monitor unit
101
. A transmitting unit A
303
converts the image signal processed by the signal processing unit A
302
into a signal having a data format suitable for wired or wireless transmission.
In the second camera unit
103
, a camera unit B
304
picks up an optical image of the subject
105
to generate an electrical signal of a predetermined type. A signal processing unit B
305
digitizes the electrical signal supplied from the camera unit B
304
to convert it into an image signal of a predetermined format. Similar to the case of the signal processing unit A
302
, the image signal converted by the signal processing unit B
305
is an image signal matching a size of an effective display area of the monitor unit
101
. A transmitting unit B
306
converts the image signal processed by the signal processing unit B
305
into a signal having a data format suitable for wired or wireless transmission.
In the monitor unit
101
, a receiving unit
307
receives image signals transmitted from the transmitting units A
303
and B
306
via wired or wireless transmission paths. A signal processing unit C
308
converts the image signal received by the receiving unit
307
into a signal of a type capable of being displayed on a display unit
309
. Specifically, the signal processing unit C
308
convert an image signal transmitted from each camera unit into an image signal matching the size and area of an image plane in which the image is displayed. The display unit
309
displays image signals transmitted from the first and second camera units
102
and
103
.
As above, in order to display the image signals transmitted from a plurality of camera units
102
and
103
on the same display screen of the image transmission system shown in
FIG. 1
or
FIG. 2
, each camera unit transmits to the monitor unit
101
an image signal matching the size of an effective display area of the monitor unit
101
. The monitor unit
101
thins the image signals so as to make them match the sizes of display areas of the main and sub image planes, and synthesizes them so as to display them on the same display screen in a superposed manner.
In order to display image signals on the main and sub image planes in a superposed manner, the monitor unit
101
processes the image signals so as not to display the image signals of the main image plane superposed upon the sub image plane. However, the conventional camera unit
102
transmits all the image signals of the main image plane, including the image signals superposed upon the sub image plane, to the monitor unit
101
. Since the camera unit
102
transmits the image signals not displayed on the camera unit
101
, a use efficiency of a transmission path is degraded and a transmission power of the camera unit
101
is consumed wastefully.
Furthermore, the monitor unit
101
thins the image signal transmitted from the camera unit
103
so as to make it match the size of a display area of the sub image plane and thereafter the thinned image signal is synthesized with the image signal of the main image plane. However, the conventional camera unit
101
transmits the monitor unit
101
the image signal matching not the display area of the sub image plane but the effective display area of the monitor unit
101
. Since the camera unit
103
transmits all the image signals including those which are thinned by the monitor unit
101
, a use efficiency of a transmission path is degraded and a transmission power of the camera unit
102
is consumed wastefully.
The above disadvantages are more conspicuous for wireless transmission paths having a limited amount of transmission data, than for wired transmission paths.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the above-described problems.
Another object of the invention is to provide an image transmission apparatus capable of improving a use efficiency of transmission paths and reducing a transmission power to be consumed.
As a preferred embodiment for such objects, the invention discloses an image transmitting apparatus, comprising: (a) receiving means for receiving first and second image signals transmitted from an external apparatus; (b) display means for displaying the first and second image signals on a same display screen; and (c) transmitting means for transmitting, to the external apparatus, information regarding a display area of the second image signal.
As another embodiment, the invention disclose
Fitzpatrick ,Cella, Harper & Scinto
Harvey David E.
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